1. Field of the Invention
The present invention generally relates to a multi-antenna device and a communication apparatus. More specifically, the present invention relates to a multi-antenna device and a communication apparatus having a plurality of antenna elements.
2. Background Information
Conventionally, multi-antenna devices with a plurality of antenna elements are known (see Japanese Patent No. 4,267,003 (Patent Citation 1), for example).
The conventional multi-antenna device includes a MIMO array antenna with a pair of antenna elements and an isolator (e.g., passive element). The antenna elements are disposed spaced apart by a distance that is one-half the wavelength λ of the corresponding electrical wave. The isolator includes an isolating element that is disposed between the two antenna elements to suppress cross coupling between the two antenna elements. The isolating element has a length that is one-quarter the wavelength λ. The isolating element is formed so as to extend in a direction in which the two antenna elements oppose each other.